1. Field of the Invention
The present invention relates to a process and to apparatus for reducing the redundancy of binary character sequences which describe characters or graphic patterns, wherein the characters or graphic patterns are represented in punctiform fashion, and more particularly to techniques wherein, in the character sequences, each binary character having a first binary value is assigned to a point which is to be represented, at least one interval corresponding to one element is provided between two points represented by the same output component, each element is broken down into a plurality of sub-elements, and wherein the binary character sequences represent the characters or graphic patterns which have been broken down into the sub-elements.
2. Description of the Prior Art
In punctiform representation of alphanumeric characters and symbols by means of a mosaic printing head or on a screen of a data viewing device or television device, the charactes are represented by matrix points. The mosaic printing head comprises either a needle printing head having a plurality of printer needles driven by moving coils or an ink printing head having a plurality of nozzles controlled by piezoceramics. The number of printer needles or nozzles is equal to the number of rows in the matrix. In this case, the output component consists of a printer needle or nozzle known as a printing component. Following operation, the earliest time at which the printer needle or nozzle can be reactuated is that following an interval of time or space which is known as an element, in this case a printing element. If the mosaic printing head provided with the printing components is moved by one entire printing element between two actuations of printing components, the resolution of the represented characters is low.
A publication by B. Peukert and H. Senger: Schreibstation PT80, Siemens-Zeitschrift 51 (1977), Vol. 4, Pages 215-218 describes a printer terminal wherein the mosaic printing head is moved only by half a printing element between two actuations of the printing components in order to improve the resolution of the represented characters. Here, the number of printing components is not increased and the length of time between two actuations of the same printing component is not shortened. A further improvement in resolution is obtained by splitting a printing element into more than two sub-elements.
If each possible printing position within a character is assigned one binary character, with the normal coding providing an equal number of printing components, it is necessary to have a quantity of information which is proportional to the number of sub-elements per printing element and which must be stored in a character generator. Each printing component is assigned binary character sequences in the character generator and the number of binary characters in each character sequence is proportional to the number of sub-elements per printing element. When several sub-elements per printing element are used, it is consequently necessary to provide character generators having a large storage capacity.
Somewhat the same applies to the representation of characters or graphic patterns by means of a laser printer on a screen of a data viewing device or the representation of characters or graphic patterns in a television device.